The invention relates to hearing aids, and more particularly relates to hearing aid receivers that are used in such aids. In its most immediate sense, the invention relates to shock and vibration-damping hearing aid receivers and to hearing aids in which such receivers are mounted.
Vibration from a hearing aid receiver can be transmitted to the shell of the aid and thereby further transmitted to the faceplate of the aid. Because the faceplate contains one or more microphones, such vibration can cause feedback. To eliminate or reduce such feedback, hearing aid manufacturers have sometimes wrapped the receiver in tape before mounting it in the hearing aid. The tape reduces the mechanical coupling between the receiver and the shell and thereby reduces the likelihood that feedback will result. It is also known to achieve this result by inserting the receiver into an elastomeric boot.
In some applications (such as canal aids or completely-in-canal xe2x80x9cCICxe2x80x9d aids), a tape-wrapped or boot-covered receiver cannot practicably be used.
Additionally, labor is required to wrap the receivers with tape or to insert them into boots.
The invention proceeds from the realization that it is feasible for the manufacturer of a hearing aid receiver to provide the hearing aid manufacturer with a receiver to which an external vibration damper has already been fixed (as by adhesive). This would save labor for the hearing aid manufacturer.
In accordance with the invention, a hearing aid receiver is permanently secured to an external vibration damping means. In one embodiment, a sound tube and at least two wires are secured to the receiver. A hollow bladder surrounds the receiver; the bladder is sealed to the sound tube and to the wires. The bladder is of a low durometer elastomer and is filled with an electrically nonconductive fluid. In another embodiment a unitary element of a low durometer elastomer is adhered externally to the receiver. This element can be a solid bead. Alternatively, this element can have a multiplicity of outwardly-extending flexible fingers that envelop the receiver when the receiver is secured to the shell.
When the receiver and vibration damping means attached thereto are inserted into the shell of a hearing aid, the vibration damping means is interposed between the receiver and the shell. As a result, vibration from the receiver is substantially if not completely damped out before it reaches the shell. Because a low durometer elastomer deforms as a result of even low forces exerted against it, even low-amplitude vibrations will cause deformation of the vibration damping means. This makes it possible to reduce the size and the mass of the receiver and vibration damping means without reducing its effectiveness.
Further advantageously, in accordance with the invention there is provided a hearing aid with improved durability. A hearing aid receiver is a delicate component and mechanical shock (such as would be produced by dropping the aid onto a hard surface) can make it nonfunctional. In accordance with the invention, some or all of such mechanical shock will be absorbed by the vibration damping means, making it more likely that a hearing aid in accordance with the invention will continue to operate after a patient drops it.